Just watched an very interesting tech talk from the Kernel subsystem maintainer Greg Kroah Hartman. He puts up an interesting statistics on the money flowing into to maintain the linux kernel. You would be amazed !!!

Amateurs [ 18.5% ]

Red Hat [ 11.6% ]

IBM [ 7.5% ]

Novell [ 6.6% ]

Unknown [ 5.5% ]

Intel [ 4.1% ]

Oracle [ 2.2% ]

Consultants [ 2.2% ]

Academia [ 1.5% ]

Renesas Tech [1.5% ]

Notably missing in the top 10 ( 61.2% ) are Google, ARM, Canonical ( Ubuntu ). I wonder how many of the rest 38% are ARM based developers. There must be a a large community as most devices these days from TI, ST, NXP etc have an ARM processor. This data was compiled by Greg in 2008 and things might have changed now. The biggest contributor is Intel mainly due to the large amount of desktop and servers are based on x86 Intel chips, Renesas known for SH4 is a surprise candidate.